Plant integration of wireless steam traps
Case study notes: Last December, a team of engineers and control system specialists worked with a client to field test the installation and operation of wireless steam trap monitors in an industrial environment.
Engineers involved in the wireless sensing and monitoring project had to address two major questions:
1) Given the amount of metal and line-of-sight obstructions, would wireless work?
2) Could the wireless devices be integrated into their existing control system?
We quickly installed 30 wireless steam trap monitors on multiple floors in our steam plant. These devices are battery-operated, so no field wiring was required, and the batteries typically last three to five years. Each trap was configured to report four instrument readings: acoustic impedance, trap temperature, battery voltage, and internal board temperature. The transmitters contain software to form a self-organizing network, which allows them to work like repeaters for each other when necessary. It also allows you to add or remove transmitters as your plant’s needs change.
Three Smart Wireless Gateways from Emerson were used to communicate with the wireless transmitters. The gateways are Web-enabled, allowing connection with a laptop or other equipment via Ethernet. It is easy to communicate with the gateways and view information from each of the traps. In addition to process information, the transmitters report which other transmitters they communicate with. This allows fine-tuning of device placement to determine if signal repeaters are needed.
A ProSoft Modbus card was configured to move the instrument readings from the gateways into the plant’s existing Allen-Bradley controllers from Rockwell Automation. Thus alarms, display, and trending of the steam trap information could be added to the existing human-machine interface system.
In the five months since the system has been in service, there have been no signal-loss problems nor any failures of the wireless transmitters or gateways. This test installation has been, and continues to be, a successful demonstration of the industrial wireless technology.
– Susan Lang is project manager, Maverick Technologies. Edited by Mark T. Hoske, content manager CFE Media, Control Engineering, Plant Engineering, and Consulting-Specifying Engineer. Reach him at firstname.lastname@example.org.
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